需要朋友字段。 （导航属性字段）

Question

因此，我正在探索ASP.NET Core（WebAPI）。我创建了2个模型，制作了上下文文件，在类 friend 和 videocollection之间添加了一对多关系。现在，当我尝试将创建数据发布到两个表中时，我会收到验证错误，因为我没有从浏览器发送导航字段。 模型：

public class Friend
{
    public int Id { get; set; }
    .....
    public virtual IEnumerable<VideoCollection> videoCollections { get; set; }
}
public class VideoCollection
{
    public int Id { get; set; }
    ......
    public int FriendId { get; set; }
    public virtual Friend Friend { get; set; }
}

我的上下文类：

public class WebApiMySQLContext : DbContext
    {
        public WebApiMySQLContext(DbContextOptions<WebApiMySQLContext> options)
            : base(options)
        {
        }
        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);

            builder.Entity<Friend>()
                .HasMany(f => f.videoCollections)
                .WithOne(v => v.Friend)
                .HasForeignKey(v => v.FriendId)
                .IsRequired();
        }

        public DbSet<Friend> Friends { get; set; } = null!;
        public DbSet<VideoCollection> Videos { get; set; } = null!;
    }

和用于后操作的控制器：

[HttpPost]
        public async Task<ActionResult<VideoCollection>> PostVideoCollection(VideoCollection videoCollection)
        {
          if (_context.Videos == null)
          {
              return Problem("Entity set 'WebApiMySQLContext.Videos'  is null.");
          }
            _context.Videos.Add(videoCollection);
            await _context.SaveChangesAsync();

            return CreatedAtAction("GetVideoCollection", new { id = videoCollection.Id }, videoCollection);
        }

每个有效的邮政

{
  "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
  "title": "One or more validation errors occurred.",
  "status": 400,
  "traceId": "00-6d1fcffc19ecf7f8e9bbf5eed016d842-f3712183c476ca8d-00",
  "errors": {
    "Friend": [
      "The Friend field is required."
    ]
  }
}

请求主体的响应主体

{
  "movietitle": "movie",
  "yearreleased": "1810",
  "rating": "1.6",
  "subject": "Violence",
  "length": "1.8",
  "note": "Bad film",
  "friendid": "1"
}

Answer 1

您应该使用ViewModels，然后可以使用AutoMapper或手动映射（自动应用程序）

public class FriendViewModel
{
  public int Id {get;set;}
  .....
  (WITHOUT IEnumerable<VideoCollection> videoCollections property)
}
public class VideoCollectionViewModel
{
  public int Id { get;set;}
  ...
  public int FriendId {get;set;}

  (WITHOUT Friend property)
}

之后，您应该映射它...
添加时不要使用任何导航属性。